The chemical diffusion coefficients of lithium ions (DLi) in spherical Li[Ni0.5Mn0.3Co0.2]O2 were systematically determined by galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS). The DLi obtained from GITT were greatly dependent on the lithium content and cell potential. In the charge process, the DLi values were in the range of 9.0 x 10−11 to 3.3 x 10−9cm2/s. In the discharge process, the DLi values were in the range of 1.9 x 10−11 to 3.9 x 10−9cm2/s. In addition, the minimum values in the DLi were observed at the stoichiometry x ≈ 0.25 for Li1−x[Ni0.5Mn0.3Co0.2]O2, which coincide with the voltage-plateau region at about 3.75 V. The DLi obtained from EIS were in the range of 1.7 x 10−11 to 6.5 x 10−9cm2/s and the variation tendency with cell potential was consistent with the results obtained from GITT during the charge process.

Determination of the Chemical Diffusion Coefficient of Lithium Ions in Spherical Li[Ni0.5Mn0.3Co0.2]O2. S.Yang, X.Wang, X.Yang, Y.Bai, Z.Liu, H.Shu, Q.Wei: Electrochimica Acta, 2012, 66, 88-93